The invention relates generally to hydraulic servo systems and more particularly it relates to an adjustable servo mechanism for setting and maintaining a predetermined amount of feeding- or absorbed pressure fluid for a hydraulic machine.
Conventional servo mechanisms of this type include a manually adjustable regulating member cooperating with a setting piston to adjust a regulating stream of fluid pressure for a follower piston coupled between the setting piston and a biased control member of a recoil device for controlling the main pressure fluid in the hydraulic machine. It has been also known in prior art servomechanisms to use a flow restricting valve to relieve the fluid pressure in the hydraulic machine in response to a predetermined limit value of the fluid pressure. The disadvantage of such known arrangements however is the fact that on the completion of the pressure relief process, the nominal value of the pressure in the machine has to be reset manually.
It is therefore an object of this invention to avoid the disadvantage of the prior art servomechanisms of this type.
In particular, an object of this invention is to provide a servomechanism that upon actuation of a flow restricting valve and the subsequent misadjustment of the hydraulic machine occurring upon the completion of the flow restricting function, automatically resets the fluid pressure to its original nominal value.
Another object of this invention is to provide a servomechanism wherein the nominal value of the desired fluid pressure is adjustable manually.
Still another object of this invention is to create the improved servomechanism with minimum structural changes in existing servomechanisms of this type.